Large injection molds are used to make a wide variety of molded items such as pails and lids. Typically, the various molded items are offered for sale in a variety of different sizes, which requires that the molding operation has to be terminated, and the complete injection mold assembly must be removed from the molding apparatus for replacement with a complete mold of different size, for molding an article of different size. To do this conventionally, the water and air lines connected to the complete mold must be disconnected. Also, the complete mold assemblies are large, bulky items which require a large storage space when not in the molding press, especially for the molding of multiple, thin-walled containers, which require close molding tolerances.
Thus, the setting up of production of a different design of molded articles is typically a rather complex and time consuming operation, requiring a plurality of expensive, complete mold assemblies.
By this invention, a modular system is provided in which significant portion of the mold is reusable in the manufacture of a number of different designs of molded articles. Particularly, it is possible for the water and air line-carrying portions of the mold to be permanently installed in the molding apparatus, with different, inner, modular cavity and core portions which define the actual molding chamber being those portions which are removed as it is desired, to mold different designs or sizes of molded articles.
Thus, the size and weight of the actual items that are replaced in the mold when a design change is desired is significantly reduced, making the operation simpler. Similarly, significant cost is saved by the reuse of portions of the mold so that, for each design of molded article, only a smaller piece of metal is required for each of an internal core-defining member and cavity-defining member. Also, there is a significant improvement in the convenience of replacing the internal mold portions, when compared with the former manner of replacing the entire mold assemblies.